Non-destructive flex testing method and means
AssigneeInternational Business Machines Corporation
InventorsSamuel M. Goldfarb, Paul R. Herb, Joseph M. Lukaitis, Leathen Shi
Life of this patent
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Abstract
Describes a process for applying non-destructive cyclical mechanical stress to planar items in order to simulate the effects of cyclical thermal stresses. Latent defects are accelerated and screened early in a manufacturing process.
Claims4
A process for testing a planar electronic component for latent defects which will cause failure during the life of the component when the component is later used, comprising the steps of:
- pre-testing the planar electronic component, as a test-piece, for detectable electrical errors in circuits in the test-piece;
- placing the test-piece into an apparatus having chambers on opposite sides of the test-piece if the pre-testing step finds the test-piece has no detectable electrical errors;
- applying pressurized filtered air to one chamber while exhausting air from the opposite chamber, and alternating this process with the chambers, to bi-directionally flex the test-piece up to a predetermined mechanical distortion at a predetermined frequency for a predetermined number of cycles, said predetermined mechanical distortion, frequency, and cycle parameters for the test piece having been determined by generalized computer stress analysis programs;
- and
- post-testing the test-piece for the existence of any detectable electrical error after the bi-directional flexing of the test-piece is completed to determine if any error condition developed in the test-piece during the bi-directional flexing.
A process for verifying parameters used in testing a planar electrical component for latent defects which can cause failure during the life of the component when the component is later used, comprising the steps of:
- performing a computer analysis of mechanical stresses due to flexing a planar electrical component while held as a test-piece in a flexing apparatus based on overall geometry and structural parameters of the test-piece;
- analyzing by a computer program of incremental mechanical stresses in incremental portions of structure in the test-piece based on coefficients of thermal expansion of materials used in construction of the test-piece over a temperature variation expected in use of the test-piece;
- comparing and correlating the mechanical stresses in the test-piece obtained from the performing step and from the analyzing step for a multiplicity of thermal cycles expected over a life-time of the test-piece;
- selecting a sample of the test-piece by pre-testing a sample and finding no detectable electrical error condition in electrical circuits of the sample;
- flexing the sample for a number of test cycles related to the multiplicity of thermal cycles at a predetermined flexing frequency at a predetermined mechanical distortion of the sample to verify a correlation between flexing and thermal stressing for the test-piece indicated by the comparing and correlating step;
- post-testing the sample to determine if the flexing step damaged the sample;
- and
- repeating the flexing step after replacing the sample of the test-piece if damaged by the afore-mentioned flexing step and changing the predetermined mechanical distortion for the flexing step.
Dependencies are inferred from the claim text.